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EPA finds low risk to human health at Superfund site near Silverton

Despite findings, agency says cleanup remains a priority
An Environmental Protection Agency study found little risk to human health within the Bonita Peak Mining District Superfund site.

A new study has found no serious risk to human health stemming from mines included in a Superfund site around Silverton, according to the Environmental Protection Agency.

“This is a good news story,” said Christina Progess, Superfund remedial project manager. “And it’s a really important milestone for the project that paints a more full picture in terms of what cleanup work needs to be done.”

The Bonita Peak Mining District Superfund site was declared in fall 2016, about a year after an EPA-contracted crew caused a blowout at the Gold King Mine, which sent 3 million gallons of mine wastewater down the Animas and San Juan rivers.

Made up of 48 mining sites considered the top polluters in the headwaters of the Animas River, the project has had a question looming over it since the beginning: Just how much threat do the sites included in the Superfund pose to human health?

“You have to have scientific evidence to back up why you need to do the work,” said San Juan County Commissioner Scott Fetchenheir. “You don’t just do it to show the public or high-level administration that you’re accomplishing something.”

EPA human health risk study
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As part of the Superfund process, the EPA must evaluate the risks contamination slated for cleanup has on human health. In the case of Bonita Peak, exposure to mine waste through incidental ingestion and inhalation stood as the highest possibilities for people who visit the area.

But, for the most part, the study showed there doesn’t seem to be much risk to human health.

The EPA didn’t find any risks to people who might be working in the area, such as road crews or ATV guides. And metals in the area didn’t pose any risk to recreational users, such as hikers, hunters or people fishing in the area.

Where health risks were found, said Steve Merritt, an EPA risk assessor, were at four dispersed camping sites north of Silverton along Country Road 2, which follows the Animas River, and at three mine sites that are used as recreational staging areas up Mineral Creek.

At the camping sites along the Animas, Merritt said tests showed a risk to children for lead exposure, both in the short and long term. At the three mine sites – Koehler, Junction and Longfellow – tests showed children were at risk for short-term exposure to arsenic.

Merritt said arsenic and lead are the main concerns in Bonita Peak. The evaluations for short-term exposure were based on a family camping at a site for two to 14 days and a child ingesting the metals through the soil and air. Long-term exposure was based on a child camping for seven to 14 days and returning every year from age 1 to 6.

Merritt acknowledged it’s not likely many people will meet these criteria, but he said the study is useful to prioritize where cleanup projects should occur.

Two of the four campsites along the Animas, as well as all three sites up Mineral Creek, have been included in the EPA’s quick action plan that is set to start this summer.

“Overall, there’s a lot of good news in here,” Progess said. “It doesn’t impact the local tourism industry, and folks working out in the district aren’t at risk from a human health standpoint. But (the study) also helps us highlight there are some areas that people come in contact with it.”

While Superfund sites with clear and significant human health risks receive priority within the EPA for funding, Progess said she doesn’t expect the study’s findings to affect Bonita Peak.

“Bonita Peak has always been and continues to be one of the administration’s top priority Superfund sites in the nation,” she said. “I don’t anticipate (funding) being a concern.”

In April, the EPA released a study assessing risks to aquatic habitats, which showed that in areas where water had low pH and elevated metals, fish and other aquatic life populations were highly impaired or nonexistent.

The study helped EPA identify four areas where the agency would like to improve water quality in the Animas River watershed to the point where restoration of aquatic life could be achievable.


EPA human health risk study (PDF)

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